1. The Field of the Invention
The present invention relates to dental bleaching compositions and methods for bleaching teeth surfaces. More particularly, the present invention is directed to dental bleaching compositions which incorporate a non-nutritive sweetener, sucralose.
2. The Relevant Technology
Since its introduction in early 1989, there has been significant interest among the dental profession and the general public for home-use tooth bleaching products and methods. In its simplest form, home bleaching products typically include a dental bleaching composition having a form of hydrogen peroxide as the active bleaching agent. Some compositions are in the form of toothpastes that are simply brushed onto the teeth during a person's daily dental hygiene routine. Other, more specialized bleaching compositions are adapted for extended contact with the teeth to be bleached, such as by means of a dental tray.
As a general rule whitening toothpastes have largely been ineffective in whitening teeth due to their relatively low potency or concentration of active bleaching agent coupled with the short duration of contact of such formulations with a person's teeth. Because of the manner in which toothpastes are manufactured, shipped, stored and sold, toothpastes are largely incapable of incorporating higher concentrations of active bleaching agents that remain stable over the intended manufacturing and storage life of the toothpaste prior to use. Moreover, it is well-known that people typically brush for 60 seconds or less, thus further reducing the effectiveness of the already low concentration bleaching agent within over-the-counter toothpastes.
In view of the foregoing, bleaching compositions having increased bleaching activity coupled with methods that maintain such dental compositions in contact with the teeth for longer periods of time are necessary to effect a noticeable bleaching effect in most people. Typical dental bleaching compositions include from 5-20% by weight of carbamide peroxide (CO(NH.sub.2).sub.2.H.sub.2 O.sub.2), which is a complex of urea and hydrogen peroxide.
Such dental bleaching compositions are typically applied to a person's teeth using a dental tray configured so as to retain the dental composition against the person's teeth. A self-sealing dental "splint" that can be used with more fluid and less sticky dental bleaching compositions are disclosed in U.S. Pat. No. Re. 34,196 to Munro. Munro recommends the use of Proxigel.RTM., manufactured according to U.S. Pat. No. 3,657,413 to Rosenthal, which at the time contained only 0.6% carboxypolymethylene as a thickening agent, or a mixture of Proxigel.RTM. and Peroxyl.RTM. gel, which is an even more fluid bleaching composition than Proxigel.RTM.. The Munro dental tray is especially suitable for use with such highly fluid dental compositions since it is made from a rigid plastic material and configured so as to form a fluid-tight seal against the person's gums. Such trays, however, are not always comfortable for the user, particularly when the dental tray is held in place over long periods of time within a person's mouth.
Flexible, more comfortable-fitting dental trays that are preferably used in combination with more sticky and viscous dental bleaching compositions are disclosed in U.S. Pat. Nos. 5,098,303 and 5,234,342, both to Fischer. Such dental trays, while being more flexible and generally thinner-walled compared to prior dental trays, are preferably trimmed in a preferred embodiment so as to terminate below the gingival margin and then scalloped up and around the interdental papilla. This provides maximum bleaching of the entire surface of the person's teeth while minimizing or eliminating actual contact with the person's gums, including the interdental papilla, thus providing minimum discomfort. Further enhancement of bleaching is provides by optionally building "reservoirs" into the dental trays so as to allow for increased loading of bleaching composition within the dental tray that can contact the teeth.
A problem with such dental bleaching composition, however, is that patients sometimes fail to use the compositions for adequate time periods due to the bitter taste of the dental bleaching agent. Attempts to camouflage the bitter taste have involved the use of a variety of sweeteners.
Nutritive sweeteners, which include sugars such as sucrose, fructose, mannose, sorbitol, mannitol, and xylitol, are unfortunately not sweet enough to disguise the bitter taste. Even when added in large quantities, such sugars simply still cannot render compositions containing bleaching agents such as peroxides and perborates to be sufficiently palatable. Additionally, tooth decay is enabled through the presence of nutritive sweeteners such as sucrose.
Non-nutritive sweeteners, which are sweeteners without caloric value, have also been utilized. An example of a non-nutritive sweetener is aspartame. Aspartame is unfortunately not stable in the presence of bleaching agents. One non-nutritive sweetener, sodium saccharine, is stable in the presence of bleaching agents. Sodium saccharine, however, has shown carcinogenic possibilities in some studies. As a result, sodium saccharine is only recommended for use by diabetics. Additionally, sodium saccharine causes an undesirable bitter after taste which compromises its usefulness in disguising the bitter taste of bleaching agents.
From the foregoing, it will be appreciated that what is needed in the art are improved compositions and methods for manufacturing suitable dental bleaching compositions that disguise the bitter taste of bleaching agents, remain stable in the presence of such bleaching agents and are not carcinogenic.
Additionally, it would be a significant advancement in the art to provide dental bleaching compositions having a stable sweetener that adequately disguises the bitter taste of bleaching agents which also had sufficient stickiness and viscosity so as to enable such compositions to adhere and retain a comfortable-fitting dental tray in place for the duration of a desired treatment regimen.
Such dental bleaching compositions and methods for their manufacture and use are disclosed and claimed herein.